Index scan with global index on replicated table may deliver wrong results
Details
| Detail name | Value |
|---|---|
| Changelog Number | 4885 |
| Type | Bug |
| Status | Resolved |
| Affected Versions | EXASOL 6.0.rc1 |
| Fix Versions | EXASOL 6.0.3 |
| Resolution Date | 2017-08-11 |
To improve scan performance the query optimizer may choose to use an existing index. With multiple filter expressions on the scan table some are covered by the index and the remaining expressions are evaluated in the traditional non-index way.
Under the following conditions the index scan delivers too may rows and hence wrong results
1) Virtually replicated scan table (new in v6, EXASOL-1798)
2) Global index chosen for index scan
3) Existence of additional scan table filter expressions not covered by the scan index columns
The bug lies therein that under above conditions the additional scan filter expressions under 3) are not evaluated correctly.
Workaround
Switch back to standard table replication: -useIncrementalReplicates=0
